JP4102946B2 - Communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data communication confirmation technique in a communication apparatus, and more particularly to a technique for confirming a reception status of transmission data in an interface set for unidirectional data communication.
[0002]
[Prior art]
As shown in FIG. 1, the conventional communication apparatus has TXD1 as transmission means, RXD2 as reception means, DTR3 as transmission permission means, and DSR4 as transmission permission confirmation means. TXD1 of communication device a5 is connected to RXD2 of communication device b6, and TXD1 of communication device b6 is connected to RXD2 of communication device a5. Similarly, DTR3 and DSR4 of the communication device a5 are also connected to DTR3 and DSR4 of the communication device b6. The communication device a5 confirms the DSR4. If the DSR4 is in the Mark state, the communication device b6 determines that transmission is not possible, and if it is in the Space state, determines that transmission is possible. Therefore, when confirming that the data transmitted from the communication device a5 has been reliably received by the communication device b6, the data is transmitted by the TXD1 of the communication device b6 to the RXD2 of the communication device a6. By analyzing the data, it can be confirmed that the data has been reliably transmitted to the communication device b6.
[0003]
[Problems to be solved by the invention]
In the conventional example of FIG. 1, it can be confirmed by bidirectional transmission / reception means whether data communication has been performed reliably. However, as shown in FIG. 2, in the case of only one-way transmission such as the communication device b6 in which only one of the receiving means RXD2 and the transmission permission means DTR3 is provided, the communication device a5 reliably transmits the transmitted data in the communication device b6. There is a problem that it is not possible to determine whether or not the signal has been received because the transmission unit TXD1 is not included.
[0004]
[Means for Solving the Problems]
The present invention solves the above problems, and the communication device of the present invention is a communication device having an interface set for unidirectional data communication, and receives data transmitted from an external device. Data transmission permission means for notifying data transmission permission or prohibition to the external device, detection means for detecting whether the data transmitted from the external device is correctly received, and data transmitted from the external device In response to the reception of the command to enter the reception confirmation mode, the communication apparatus enters the data reception confirmation mode, and a predetermined signal corresponding to the detection result of the detection unit is applied to the output signal line of the data transmission permission unit for a predetermined period. And transmitting means for sending out.
[0005]
The communication device of the present invention is suitable for use in combination with the above communication device, and is a communication device having an interface set for unidirectional data communication. A first transmission means for transmitting data; a reception means for receiving a notification of permission or prohibition of data transmission to the external apparatus, transmitted from the external apparatus; and data reception of the external apparatus to the external apparatus A determination unit that detects a state of the input signal line of the reception unit for a predetermined period after transmitting the command to be in the confirmation mode, and determines whether or not data is correctly received in the external device according to the detected state; It is characterized by that. In this case, prior to the transmission of the predetermined data, it may be configured to have means for transmitting predetermined data for selecting an external device.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a diagram showing an embodiment of the present invention. A communication device a5 has a transmission means TXD1, a transmission permission confirmation means DSR4, an ACK / NACK confirmation means 7 as a reception confirmation means, a communication device b6 has a reception means RXD2, and a transmission. Permission means DTR3 and ACK / NACK transmission means 8 are provided as reception confirmation transmission means. The transmission means TXD1 of the communication device a5 is connected to the reception means RXD2 of the communication device b6. The transmission permission confirmation unit of the communication device a5 is connected to the transmission permission unit DTR3 of the communication device b6. In this embodiment, the ACK / NACK confirmation unit 7 and the ACK / NACK transmission unit 8 are connected to share the DSR4 / DTR3 line.
[0007]
Next, the operation of this example in the above configuration will be described. When data is transmitted from the communication device a5 to the communication device b6, the communication device b6 receives the data. If an error occurs during data reception, the communication device b6 detects the error and stores the result in a predetermined memory. The communication device a5 transmits a command to enter the data reception confirmation mode to the communication device b6 in order to determine whether the communication device b6 has detected an error or has received data normally. When the communication device b6 receives the command, it enters the data reception confirmation mode, and the ACK / NACK transmission means 8 sends a signal indicating the success or failure of communication on the DTR. FIG. 4 is a diagram showing the waveform change, FIG. 4a is an ACK waveform 12 indicating that the signal has been normally received, and FIG. 4b is a NACK waveform 13 indicating that an error has occurred.
[0008]
When the data is normally received, that is, when the data indicating the occurrence of the error is not stored in the predetermined memory, the ACK / NACK transmission means 8 of the communication device b6 periodically receives the DTR signal for t time Mark. The state, the t-time Space state, and the DTR line are changed. If the number of times of this change is set as a predetermined number, the change is counted by the ACK / NACK confirmation means 7 in the communication device a5 and compared with the predetermined number of times, a more reliable confirmation is possible. However, in order to reduce the burden on a sequencer such as a CPU that implements the ACK / NACK confirmation means 7, the duration of the Mark state and the duration of the Space state are each measured at least once and compared with the t time. You may confirm by. The ACK / NACK confirmation unit 7 can be realized by using a timer, an event counter or the like built in the one-chip microprocessor, for example.
[0009]
When an error occurs, that is, when data indicating the occurrence of the error is stored in the predetermined memory, the DTR 3 is maintained in the Mark state. At this time, the error occurrence information stored in the predetermined memory is erased. In the communication device a5, after the command is transmitted, the ACK / NACK confirmation means 7 detects the state of the DSR line to determine whether or not the data transmitted by the communication device b before the command transmission has been received reliably. The determination is performed according to the configuration and procedure as described above, and if no change in Mark or Space is detected, it is determined that a communication error has occurred. When the communication device a5 finishes the determination process, the communication device a5 transmits a command to end the data reception confirmation mode. When this command is received, the ACK / NACK transmission means 8 of the communication device b6 sets the DTR 3 to the Space state if data reception is possible according to the state of the communication device b6, and to the Mark state otherwise.
Since the DTR 3 is also defined as a signal for permitting or prohibiting the transmission of data to the communication device a5, the time functioning as a signal for notifying the result of this command can be specified in advance. For example, the command result, that is, the presence / absence of a communication error may be notified for a predetermined period after the transmission of this command, and thereafter, the data reception confirmation mode may be terminated to indicate permission / prohibition of data transmission. The predetermined time is preferably at least 2 t hours. Thereby, it is possible to omit the command for ending the data reception confirmation mode.
[0010]
FIG. 5 is a diagram showing a pattern change of another DTR line for distinguishing between a normal state and an error state. FIG. 5A is an ACK waveform 14 showing a case of normal reception, and the DTR line is marked and marked every t1 time. And change. FIG. 5b shows a case where the communication device b6 is normally received by comparing the space period with the communication device a5 by repeating the Mark state for t1 time and repeating the Space state with t2 time in the NACK waveform 15 indicating the case where an error has occurred. It can be confirmed whether or not.
[0011]
FIG. 6 is a diagram showing another embodiment of the present embodiment, in which the communication means TXD1 of the communication apparatus a5 is connected to the reception means of the communication apparatus b6 and the communication apparatus c11, and the transmission permission confirmation means DSR4 of the communication apparatus a5 The communication device b6 and the transmission permission confirmation means DTR3 of the communication device c11 are connected. The communication device a5 is provided with device selection means 9 and is connected to the transmission means TXD1. On the other hand, the communication devices b6 and c11 are provided with the reception data determination means 10 and are connected to the reception means RXD2. The communication device a5 selects the communication device b6 or c11 by the device selection means 9.
[0012]
From the device selection means 9, data for selecting the communication device b6 or c11 is transmitted as a command via the transmission means. The communication devices b6 and c11 that have received this command analyze the command by the received data determination means 10 and determine whether or not they are selected. As a result of the determination, if it is not selected, the communication device b6 ignores subsequent data as not being addressed to itself until it is selected by the command.
[0013]
On the other hand, the communication device selected by the command receives subsequent data as data addressed to itself. Accordingly, the communication device a5 can confirm the reception state of the selected communication device by using the ACK / NACK confirmation means 7 by transmitting the communication device selection command prior to the transmission of the data reception confirmation mode command. I can do it. In this embodiment, the device selection means 9 is configured to send a command, but a data string for device selection that can be judged by the reception data judgment means 10 of the communication devices b6 and c11 is added to the head of the data string to be transmitted. It is good also as a structure.
[0014]
【The invention's effect】
As described above, according to the communication device of the present invention, even a communication device capable of only one-way data transmission and reception can confirm the reception state and establish reliable data transmission and reception. In addition, reliable data transmission and reception can be established even in a one-to-many connection state.
[Brief description of the drawings]
FIG. 1 is a diagram showing a conventional communication apparatus.
FIG. 2 is a diagram showing another conventional example.
FIG. 3 is a diagram showing an embodiment of the present invention.
FIG. 4 is a diagram showing changes in DTR waveform according to an embodiment of the present invention.
FIG. 5 is a diagram showing changes in DTR waveform according to another embodiment of the present invention.
FIG. 6 is a diagram showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Transmission means 2 ... Reception means 3 ... Transmission permission means 4 ... Transmission permission confirmation means 5 ... Communication apparatus a
6. Communication device b
7... ACK / NACK confirmation means 8... ACK / NACK transmission means 9... Device selection means 10.
12 ... ACK waveform 13 ... NACK waveform 14 ... ACK waveform 15 ... NACK waveform

Claims (3)

A communication device having an interface set for unidirectional data communication,
Receiving means for receiving data transmitted from an external device;
Data transmission permission means for notifying the external device of permission or prohibition of data transmission;
Detecting means for detecting whether the data transmitted from the external device is correctly received;
In response to the reception of the command for setting the data reception confirmation mode transmitted from the external device, the communication device enters the data reception confirmation mode, and the output signal line of the data transmission permission unit responds to the detection result of the detection unit. A communication apparatus comprising: a transmission unit that transmits a predetermined signal for a predetermined period. A communication device having an interface set for unidirectional data communication,
First transmission means for transmitting data to an external device;
Receiving means for receiving notification of permission or prohibition of transmission of data to the external device, transmitted from the external device;
After transmitting a command for setting the external device to the data reception confirmation mode to the external device, the state of the input signal line of the receiving means was detected for a predetermined period, and whether the data was correctly received in the external device accordingly A communication device comprising: determination means for determining whether or not. 3. The communication apparatus according to claim 2, further comprising second transmission means for transmitting predetermined data for selecting the external apparatus prior to transmission of the command .

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